The long range goal of the proposed research program is to characterize the role of the hypothalamic and extra-hypothalamic neurons in the control of anterior pituitary function. More specifically, attempts will be made to delineate the underlying neural mechanisms responsible for signalling the release of hypothalamic releasing hormones. Studies will be conducted using the techniques of single unit recording, antidromic and orthodromic identification, and microelectrophoresis to specify the activity level, afferent and efferent connectivity, and pharmacologic sensitivity of hypothalamic and extra-hypothalamic neurons. Particular attention will be focused on those neurons which project to the median eminence. Transmitter pharmacology at the afferent synapse will be investigated by comparing orthodromic potentials with those induced by putative neurotransmitters. The receptor mechanism at the afferent post-synpatic membrane will be studied by utilization of putative neurotransmitters and their blocking agents. In addition, the hormonal status of the animal will be manipulated in order to assess the effect of such manipulations on the above-mentioned neural parameters. It is hoped that the information obtained from the proposed projects will aid in the understanding of how neural signals are converted to hormonal events.